Drivers are being advised to allow more time for their journeys or consider alternative routes around Wickham.
The annual event on Monday, May 21 is expected to see more than 1,000 travellers attend.
It will have the traditional horse-run, fairground rides and market stalls.
Closures will include the A334 between the traffic lights at Blind Lane and the roundabout junction of the A32 between 5am and 8pm on Monday.
Wickham Square will be closed from midday on Sunday to 8pm on Monday.
Arrangements have been made for horse boxes to be parked on the east side of the A334 between the north end of the square and the junction at Blind Lane and Titchfield Lane.
Any vehicle parked in an unauthorised place will be towed away - signage has been placed along the route to provide advance information about the road closures.
Permits have been provided for residents to allow access through the closure points, although the road next to the entrance to The Square will not be passable due to the presence of horses and crowds.
A dedicated emergency telephone number has been set up for residents in the roads where access to their properties is affected. They have been contacted directly with this information.
Officers in high visibility uniform will be on duty throughout the event.